Trying to think of a use case I thought of wireless + wired, would be kind of neat if they had the same IP. But that falls apart completely if you have them connected at the same time (which I often do).
We’re there any obvious issues in such a setup?
I'm not sure how it'd fit into a Network Manager or systemd world. There really wasn't any particular trick to it, IIRC I used link monitoring to detect link failure, though I might have used ARP, and set the ethernet as the primary interface, just using the standard Linux bond driver.